1. Technical Field
The present invention relates generally to an X-ray shielding device and, more particularly to an X-ray shielding device for preventing a patient from being exposed to a portion of X-ray radiation in an X-ray fluoroscopic apparatus.
2. Background Art
In medical applications, diagnosis based on an X-ray fluoroscopic apparatus has been traditionally carried out. More recently, the X-ray fluoroscopic apparatus has been also used for treatment procedures in addition diagnosis procedures.
It has been common to treat a patient, for example, suffering from cranial aneurysm by open brain surgery under general anesthesia, but, recently, not a few intravascular surgeries may be conducted. The intravascular surgery may be conducted based on a microcatheter which is delivered through a blood vessel, which may involve use of an X-ray fluoroscopic apparatus (an angiographic system). Such an intravascular surgery may conveniently require no large incisions in the human body and be less invasive.
When the X-ray fluoroscopic apparatus is adapted to be used for treatment, however, it can be forced to irradiate the human body with X-ray radiation for relatively longer irradiation time, as compared to diagnosis. Also, X-rays may be emitted to not only a site of the human body requiring the fluoroscopy, but also an adjacent site of the human body requiring no fluoroscopy.
It will be understood that such an undesirable medical exposure of the patient, in particular certain sites of the human body should be reduced or even eliminated as far as possible. Such reduction in the X-ray exposure is very important for some human body site less resistive to radiation, i.e. requiring less exposure dose. For example, in the case of intravascular surgery on the human cranial region or head, the reduction in the exposure of human eyeballs, in particular lenses thereof is absolutely important from the standpoint of prevention of cataract.
Japanese Laid-Open Patent Application No. 2004-49849 discloses an X-ray shielding device used in conjunction with an X-ray fluoroscopic apparatus and intended to reduce the undesirable medical X-ray radiation exposure as mentioned above. The disclosed X-ray shielding device includes a radiation shielding disk made of lead disposed the head of the patient and an X-ray tube of the X-ray fluoroscopic apparatus situated below the patient head. The shielding disk can be translated in an X-Y plane and also tilted at a desired angle about an X axis, which shielding disk may be in turn adapted to be rotated about a Z axis. While the X-ray tube radiates X-rays in the Z axis direction, the X-rays is caused to be continuously shielded by a circular area defined the shielding disk being rotated.
Such conventional X-ray shielding device may require a complex operating mechanism which allows the pivotal and continuous rotating movements of the shielding disk about the X and Z axes, respectively in addition to the translational movement in the X-Y plane thereof.
Typically, the X-ray shielding lead disk may be situated in an upright position or in the Z axis direction. This is not feasible in terms of design considerations because of a limited space between the head of the patient and the X-ray tube of the X-ray fluoroscopic apparatus. In addition, displacement of an X-ray source of the X-ray fluoroscopic apparatus may require a temporal interruption of the operation and then a manual repositioning of the shielding disk in place.
It is an object of the present invention to solve the problems as described above, and to provide an X-ray shielding device for use with an X-ray fluoroscopic apparatus that is adapted to provide a better space-saving configuration and make effective use of a limited space available in a medical environment and also that can be arranged in such a manner to automatically move an X-ray shielding disk in synchronization with movement of the X-ray source to shield a particular site or area of a subject from the X-ray radiation.
In order to the above object, the present invention provides an X-ray shield device for use with an X-ray fluoroscopic apparatus for fluoroscopically visualizing a certain site of a subject, comprising an X-ray generator containing an X-ray source, an X-ray detector associated with the X-ray generator and including a projection plane disposed opposed to the X-ray source, and a support member disposed between the X-ray source and the projection plane independently of the X-ray detector for supporting the subject, the X-ray shield device being adapted to prevent a specified site of the subject from exposure to the X-ray from the X-ray source, said X-ray shield device comprising at least one X-ray shielding plate positioned between the X-ray source and the support member; a shielding plate driving mechanism including a supporting portion for supporting said X-ray shielding plate, said shielding plate driving mechanism being operable to move the shield plate supported by the supporting portion in a direction transverse to a path of X-ray irradiation; and a control unit for controlling operation of said shielding plate driving mechanism to cause it to move said shielding plate in a manner so as to shield said specified site of the subject from the X-ray from the X-ray source of the X-ray generator upon movement of the X-ray generator and the X-ray detector relative to the support member.
In the X-ray shield device according to the present invention, preferably, said supporting portion of the shielding plate driving mechanism is operable to support selected one of said X-ray shielding plates of different sizes for exchange.
In accordance with one aspect of the present invention, preferably, said control unit is operable to move said X-ray shielding plate to a shielding position on which said X-ray shielding plate is to be centered and at which a line extending centrally through the X-ray source and the specified site of the subject to be shielded from the X-ray irradiation from the X-ray source, intersects a plane in which said shielding plate is moved.
In accordance with another aspect of the present invention, preferably, the X-ray shield device also comprises a shielding position determining means for determining said shielding position, said control unit being operable to move said X-ray shielding plate to said shielding position determined by said shielding position determining means.
In accordance with another aspect of the present invention, preferably, said shielding position determining means comprises; a position of X-ray source measuring device for measuring the position of the X-ray source S relative to a common reference point; a position of shielding plate driving mechanism measuring device for measuring the position of the shielding plate driving mechanism relative to said common reference point; a position of non-irradiation site measuring device for measuring the position of said specified site relative to said common reference point; and a computing unit for computing said shielding position based on data from said X-ray source position measuring device, data from said shielding plate driving mechanism position measuring device and data from said non-irradiation position measuring device.
In accordance with still another aspect of the present invention, preferably, said control unit is operable to move said X-ray shielding plate to a shielding position on which said X-ray shielding plate is to be centered and at which a line extending centrally through the X-ray source and a position of an image of the specified site of the subject on a projection plane where the specified site of the subject is projected, intersects a plane in which said shielding plate is moved.
In accordance with still another aspect of the present invention, preferably, the X-ray shield device further comprises a shielding position determining means for determining said shielding position, said control unit being operable to move said X-ray shielding plate to said shielding position determined by said shielding position determining means.
In accordance with another aspect of the present invention, preferably, said shielding position determining means comprises; a position of X-ray source measuring device for measuring the position of the X-ray source relative to a common reference point; a position of shielding plate driving mechanism measuring device for measuring the position of the shielding plate driving mechanism relative to said common reference point; a position of non-irradiation site projection image measuring device for measuring the position of the image of said specified site of the subject that is projected on the projection plane relative to said common reference point; and a computing unit for computing said shielding position based on data from said X-ray source position measuring device, data from said shielding plate driving mechanism position measuring device and data from said non-irradiation site's projection image position measuring device.
In accordance with still another aspect of the present invention, preferably, the X-ray shield device further comprises a shielding plate size determining means for determining a size of said X-ray shielding plate to be placed at said shielding position that is suitable for said specified site of the subject to be shielded from the X-ray irradiation from the X-ray source.
In accordance with another aspect of the present invention, preferably, said shielding plate size determining means comprises; said shielding position determining means, a size of non-irradiation site storing device for storing data relating to the size of a non-irradiation site of the subject projected onto a plane perpendicular to the center line which passes through the X-ray source and the center of the non-irradiation site, and a computing unit for computing the size of the X-ray shielding plate suitable for the non-irradiation site of the subject based on data provided from said shielding position determining means and data provided from said non-irradiation site's size storing device.
In accordance with still further aspect of the present invention, preferably, the X-ray shield device further comprises an X-ray shielding plate exchanging means for exchanging said X-ray shielding plate supported by said supporting portion of the X-ray shielding plate driving mechanism for another X-ray shielding plate of different size.
In accordance with another aspect of the present invention, preferably, said shielding plate exchanging means comprises a shielding plate rack for releasably holding more than one X-ray shielding plates of different sizes; said supporting portion of the X-ray shielding plate driving mechanism is configured to releasably support said X-ray shielding plate; and said X-ray shielding plate driving mechanism is constructed to move the supporting portion thereof in such a manner that the supporting portion is caused to pass the X-ray shielding plate supported thereby onto said shielding plate rack which can hold that X-ray shielding plate and to receive thereon selected one of X-ray shielding plates held by the shielding plate rack.
In accordance with still another aspect of the present invention, preferably, said control unit is operable to control said X-ray shielding plate exchanging means in such a manner that said supporting portion of the X-ray shielding plate driving mechanism is caused to pass the X-ray shielding plate supported thereby onto said shielding plate rack which can hold that X-ray shielding plate and to receive thereon an X-ray shielding plate of X-ray shielding plates held by the shielding plate rack whose size is determined by said shielding plate size determining means.
In accordance with another aspect of the present invention, preferably, said shielding plate driving mechanism is adapted to move the X-ray shielding plate along said path of X-ray irradiation.
In accordance with still another aspect of the present invention, preferably, the X-ray shield device further comprises a command input unit operatively connected to said control unit.
In accordance with another aspect of the present invention, preferably, said X-ray shield device comprising at least two X-ray shielding plates positioned between the X-ray source and the support member in order to prevent a plurality of specified sites of the subject from exposing to the X-ray from the X-ray source, and at least two shielding plate driving mechanism each operable to move the respective X-ray shielding plate, each of said shielding plate driving mechanisms being adapted to move the respective X-ray shielding plate in a direction transverse to a respective path of X-ray irradiation at a different position on said X-ray irradiation path.
As can be appreciated by those skilled in the art, the present invention provides an X-ray shield device having a better space-saving configuration and capable of being arranged in such a manner to automatically move an X-ray shield plate in synchronization with movement of the X-ray source to shield a particular site or area of a subject from the X-ray radiation.